Streaming HD movies stutter from HTPC to tv

So I ended up not purchasing any additional streaming boxes since My Movies will do so from my HTPC to my laptop. After I set it up, everything plays fine except for the HD mkv movies. They stutter. I am using my laptop wirelessly and it is a dual core with 8 gigs of ram. I tried it on another desktop, the streaming of HD flicks, and the same stutter occurs. I have att as my ISP and using their wireless network. If I manually hooked up the laptop by ethernet to the the cable box connected to my tv, will that increase the bandwith? Or is there anyway to increase the wireless to stream the HD flicks? Any help would be appreciated.